TRANSPORTATION ADVISORY BOARD AGENDA ITEM
ACTION REQUESTED:
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Receive the evaluation of traffic concerns on Jackson Avenue and Jefferson Avenue
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DEPARTMENT: Transportation, Engineering and Development
SUBMITTED BY: Michael Prousa, Transportation Manager
BACKGROUND:
In 2019, an evaluation of traffic along Jefferson Avenue from the river to Webster Street was conducted by staff, along with a consultant, as part of a traffic study for the West Side neighborhood. This section of Jefferson Avenue was included in that study. Speeds and volumes were collected at the intersection with West Street along with mid-block locations on Jefferson Avenue. The study showed speeds and volumes that were within or below the City’s typical thresholds for a collector street. The study also found that Jefferson Avenue and West Street did not meet the Manual on Uniform Traffic Control Devices (MUTCD) warrants for all-way stop installation.
Due to the intersection being a seasonal primary pedestrian crossing, the study recommended that curb extensions be installed on the west leg of the intersection of Jefferson Avenue and West Street to reduce the crossing distance, improve sight lines, and force slower vehicular movements.
In November of 2023, a resident reached out to the Transportation, Engineering and Development (TED) Business Group with concerns regarding speeding and requesting stop control on Jefferson Avenue at West Street. The planned curb extensions were under design for construction during 2024. Speed data was collected on Jefferson Avenue in December of 2023 to establish a recent baseline prior to construction of the curb extensions and to be responsive to the resident concern. The data collected indicated speeds are within the typical thresholds for a collector street.
In the summer of 2024, the resident reached back out to staff along with the City Council to express more concerns about perceived speeding on Jefferson Avenue. At the September 17th, 2024, City Council meeting, Council requested that staff evaluate Jefferson Avenue for speeding, along with evaluating Jefferson Avenue and West Street, Jefferson Avenue and Ewing Street, and Jackson Avenue and Ewing Street for stop control.
DISCUSSION:
Speed and Volume Evaluation
When reviewing speed data on a street, the 85th percentile speed is the primary consideration. Per the Institute of Transportation Engineers, the 85th percentile speed is the speed at which 85 percent of free-flowing vehicles are traveling at or below. Use of the 85th percentile speed is based on the theory that the large majority of drivers are reasonable and prudent, do not want to have a crash, and desire to reach their destination in the shortest time possible.
The City’s Master Thoroughfare Plan classifies streets based upon their function, access, and connectivity. Jackson Avenue is classified as a Local Street (provides access to residences and businesses within a neighborhood). Jefferson Avenue is classified as a collector street (connect local and neighborhood connector through or adjacent to multiple neighborhoods and have continuity between arterial streets). The City has been collecting annual speed and volume data on 40-50 segments of road for the past 25 years. With this data, staff has established typical speeds and volumes for most road classifications.
Below is a table of the city-wide typical speeds and volumes.
|
Roadway Classification |
City-wide Typical 85th-Percentile Speed Range |
City-wide Typical Weekday Volume (Two-way) |
|
Collector Street |
29 - 34 mph |
5,000 - 12,000 vpd |
|
Neighborhood Connector |
29 - 34 mph |
500 - 5,000 vpd |
|
Local Street |
27 - 32 mph |
0 - 1,500 vpd |
In response to the concerns raised, TED staff conducted speed studies on Jackson Avenue and Jefferson Avenue at four locations:
• Jackson Avenue between West Street and Ewing Street
• Jefferson Avenue between Parkway Drive and West Street
• Jefferson Avenue between West Street and Ewing Street
• Jefferson Avenue between Ewing Street and Mill Street
The table below details the speed and volume data collected at each location on Jackson Avenue and Jefferson Avenue. See attachments for the speed data locations.
|
Jackson Avenue between West Street and Ewing Street |
|
Eastbound 85th percentile speed |
31 mph |
|
Westbound 85th percentile speed |
31 mph |
|
Vehicles per day |
2,875 |
|
Study Date |
7/22/2024 - 7/26/2024 |
|
Jefferson Avenue between Parkway Drive and West Street |
|
Eastbound 85th percentile speed |
29 mph |
|
Westbound 85th percentile speed |
31 mph |
|
Vehicles per day |
5,984 |
|
Study Date |
10/3/2024 - 10/10/2024 |
|
Jefferson Avenue between West Street and Ewing Street |
|
Eastbound 85th percentile speed |
29 mph |
|
Westbound 85th percentile speed |
31 mph |
|
Vehicles per day |
5,366 |
|
Study Date |
9/26/2024 - 10/3/2024 |
|
Jefferson Avenue between Ewing Street and Mill Street |
|
Eastbound 85th percentile speed |
29 mph |
|
Westbound 85th percentile speed |
29 mph |
|
Vehicles per day |
5,237 |
|
Study Date |
9/26/2024 - 10/3/2024 |
The tables show that Jackson Avenue and Jefferson Avenue have speeds that are within the typical threshold ranges for their street classifications.
The volume on Jackson Avenue is higher than the typical range for a local street. Data was collected on Jackson Avenue during the summer when Centennial Beach is open and higher traffic is expected during those three months.
When looking at tools that can be used to reduce vehicle speeds, the City uses the Traffic Calming Toolkit that was approved by City Council in 2021. Based on the data collected, City staff does not recommend implementing any traffic calming measures along Jackson Avenue or Jefferson Avenue at this time.
Stop Control Evaluation
City staff also reviewed Jackson Avenue and Ewing Street, Jefferson Avenue and West Street, and Jefferson Avenue and Ewing Street for all-way stop control.
Stop signs are used to assign right-of-way control and not to prevent speeding. Drivers typically go faster in between stop signs to make up for lost time. Unwarranted stop signs also create stop compliance issues because of the lack of conflict with vehicles. For these reasons, stop controls are only recommended when defined warrants are met.
Jackson Avenue is a local street, which according to the section 11-1-4 of the City’s Municipal Code, “Intersections involving residential all-way stop signs shall conform with the policy provisions of the City’s current residential all-way stop warrant.” The residential all-way stop sign warrants look at crash history, vehicle volumes, bicycle and pedestrian volumes, and other factors to determine if an all-way stop sign is warranted. Based upon the data and analysis, Jackson Avenue and Ewing Street did not meet the thresholds for consideration of an all-way stop.
Jefferson Avenue is a collector street, which according to section 11-1-4 of the City’s Municipal Code, “The placement and erection of all-way stop signs at intersections involving collector and arterials streets, as identified in the City’s master thoroughfare plan, shall conform with the regular MUTCD warrant.” For Jefferson Avenue and West Street and Jefferson Avenue and Ewing Street, staff used the Multi-Way Stop Application in Section 2B.07 of the MUTCD for the evaluation. Based upon the data and analysis, Jefferson Avenue and West Street and Jefferson Avenue and Ewing Street did not meet the thresholds in the MUTCD for consideration of an all-way stop.
Curb Extension Evaluation
The curb extensions were installed at Jefferson Avenue and West Street in August 2024 to shorten the pedestrian crossing distance and calm vehicular traffic. When traffic calming measures are installed, staff typically waits six months to one year to evaluate the impact on vehicle speeds. However, data was collected one month after installation to be responsive to the request from City Council. As previously noted, in December of 2023, staff completed a speed study at Jefferson Avenue and West Street before the curb extensions were installed to establish a baseline. The results of that study compared to the recent study are shown in the table below.
|
Jefferson Avenue between West Street and Ewing Street |
|
|
December 2023 |
September/October 2024 |
|
Eastbound 85th Percentile |
28 mph |
29 mph |
|
Westbound 85th Percentile |
34 mph |
31 mph |
The data collected shows a small increase in speeds for eastbound traffic and a large decrease in speeds for the westbound traffic. While this data looks promising for the impact of the curb extensions, staff will collect additional data in 2025 to conduct a full evaluation of the impacts of the curb extensions at Jefferson Avenue and West Street, as well as at Mill Street and Douglas Avenue. These curb extensions were also installed in 2024 based on the recommendation from the West Side neighborhood study.